wiring question - 1935B cab

[0 2339]

hey gang, just received this pretty thing and saw the wiring differs from what i've seen after a quick search:

bottom right speaker seems to have the wires switched - connection coming from the jack should go to - terminal of the speaker; + should go to the - terminal on the speaker above according to this layout:

can i keep this wiring without any harm, or should i heat up the soldering iron?

thanks

 

[fitz]

hey gang, just received this pretty thing and saw the wiring differs from what i've seen after a quick search:

bottom right speaker seems to have the wires switched - connection coming from the jack should go to - terminal of the speaker; + should go to the - terminal on the speaker above according to this layout:

can i keep this wiring without any harm, or should i heat up the soldering iron?

thanks

Yes, that looks wrong at the lower right speaker.
Your cab looks "mostly" wired parallel/series, the diagram from Scumback is showing series/parallel.
Also, your pic doesn't show the connections at the jack.
Put a meter on a speaker cable in the jack and see what you're getting.

 

[0 2339]

thanks mate, reads fine: 13.8 ohm... jack and everything else is wired just like the scumback series-paralell drawing. is this one speaker gonna be oop?

 

[fitz]

Looking at it again, the angle on your pic is deceiving.
Just noticed the series wiring on the left side, and can't tell what's going on on the right side.
If the red on the right side is the series return and you're getting 13.8, I think it's ok.

 

[0 2339]

thanks again, still not sure what to do
red on the right bottom side is not the return from the speaker above but directly connected to the "-" terminal of the jack... everything else fits the wiring according to the scumback drawing - except this bottom right speaker (top right on the drawing).

 

[fitz]

thanks again, still not sure what to do
red on the right bottom side is not the return from the speaker above but directly connected to the "-" terminal of the jack... everything else fits the wiring according to the scumback drawing - except this bottom right speaker (top right on the drawing).

Invert the Scumback drawing, and I think you'll find everything matches.

 

[0 2339]

hehe, thanks for your patience. printed the drawing, sat before the cab and nope, it's not correct. i think i'll just heat up the soldering iron... built amps that serve me well for years, but really didn't want to touch there

i marked in blue the terminals that are soldered incorrect/switched at the moment

black from input jack is wired to the ´+´ terminal of the bottom right where it should go to the ´-´ terminal. i'll just flip the 2 wires on the bottom right and it should be fine... i hope

 

[fitz]

Hard to see what black wire is going to what lug in this pic.

 

[0 2339]

yeah, it's bit hard trying to get all 4 speaker connections on a single shot... black wire coming up from the jack is going to the ´+´ terminal. black wire from ´-´ terminal goes up to the speaker above...

 

[fitz]

Should be (+) to (-) between the two, so I think you are correct to switch them.

 

[0 2339]

yea, did it and it reads 14.4 ohms now... thanks again for lending me a second pair of eyes, really appreciate it time to put them through their paces!!

 

[neikeel]

The speakers have been out and rotated. The tabs should be rotated 90 degrees inwards, other than that it looks correct.
Should look like this:

 

[0 2339]

yep, might adress that one day... for now it sounds just glorious as is lord have mercy

 

[kuli]

Do the battery test, if all cones moves in the same direction, you are good to go.
I have seen some old Celestions with polarity switched (I currently have one T1220 from 66 or 67 where + and - are switched)

 

[Ken Underwood]

If one speaker is the wrong way round then it will be out of phase to the other three, think about that

 

[0 2339]

Do the battery test, if all cones moves in the same direction, you are good to go.
I have seen some old Celestions with polarity switched (I currently have one T1220 from 66 or 67 where + and - are switched)

thanks kuli & ken. would i have to remove all the wiring? not sure, but isn't DC bad for speakers? gonna give it some more listening today, but honestly can't imagine some phase issues given the sound...

 

[Chris-in-LA]

thanks kuli & ken. would i have to remove all the wiring? not sure, but isn't DC bad for speakers? gonna give it some more listening today, but honestly can't imagine some phase issues given the sound...

Then there must have been a phase issue when you first got it. How did it sound before you switched the wires?

 

[0 2339]

Then there must have been a phase issue when you first got it. How did it sound before you switched the wires?

i didn't even plug it in as it's my first venture into pulsonic land and i was nervous af

 

[Ken Underwood]

Don't hesitate, just rewire the complete cabinet, then you will know that all is well, this being the only way to be sure.

 

[0 2339]

Don't hesitate, just rewire the complete cabinet, then you will know that all is well, this being the only way to be sure.

thanks, but i'm already sure that the wiring now matches 100% with the series-parallel drawing i posted in my op. bit unsure after kuli's post stating switched polarity on an original, but i'm pretty confident after firing it up yesterday that everything's fine and there's no weird phase issues